The present invention relates to an improved air conditioner and heater with an improved heat pipe array thermally connected to a pre-selected number of thermoelectric modules. The air conditioner may include a heater component.
Conventional cooling systems using thermoelectric modules suffer from various limitations and relatively low heat transfer efficiency. By way of example, Korean patent 2000-54406 is an example of an earlier cooling system using a thermoelectric module and conventional heat transfer arrangement. An example of another earlier heat transfer system employing a heat transfer pipe without thermoelectric module components, is described in Korean patent number 190443. Other examples of earlier systems include: U.S. Pat. No. 6,354,086 to Inoue et al., U.S. Pat. No. 5,232,516 to Hed, U.S. Pat. No. 5,269,146 to Kerner, U.S. Pat. No. 5,540,567 to Schirpke et al., U.S. Pat. No. 5,653,111 to Attey et al., and U.S. Pat. No. 5,675,973 to Dong. The foregoing examples describe conventional fluid pumping and piping systems for transportation of fluid within the heat transfer or cooling systems described in those patents.
Some of the earlier systems have attempted to improve the efficiency of heat exchange by incorporating complex fluid agitators. U.S. Pat. No. 6,354,086 to Inoue et al. is an example of an earlier patent in which such agitators are described. U.S. Pat. No. 5,269,146 describes a closed system heating and cooling system for thermally insulated containers such as portable refrigerated chests, heated bottles and serving carts for hotels and restaurants. Thermally conductive fluid is circulated through a closed loop circulating system. The heated or cooled fluid is passed through an air core heat exchanger for heat exchange with surrounding ambient air. The patent describes that the fluid is pumped at high speeds through the closed system to promote efficient heat transfer.
These earlier systems have not addressed the advantages of providing heat exchange systems having the improved efficiencies associated with harnessing the natural forces and inherent fluid flow characteristics of the capillary flow systems described below.
Many of the earlier, conventional heat transfer systems do not provide for an efficient structure or method for distributing the cooling effect of thermoelectric modules provided in cooling systems such as cooling-type air conditioners. The overall efficiency of the cooling device depends to a substantial part upon the ability of the device to effectively utilize the cooling power of the array of thermoelectric modules. In effect, it is desirable to provide a system in which there is an efficient heat transfer interface between the cooling faces of the thermoelectric modules and the circulatory system to distribute the xe2x80x9ccold supplyxe2x80x9d furnished by the cooling faces of the thermoelectric modules.
In one aspect of the invention, a cooling manifold is used in which the manifold comprises an upper cylinder, a lower cylinder and a plurality of vertically arranged heat pipes providing fluid communication between the upper and lower cylinders. Each of the heat pipes is a generally, planar, elongated member extending between the upper and lower cylinders. The manifold defines an interior volume for closed circulation of a thermally conductive fluid. In a preferred embodiment, the upper and lower cylinders and interconnecting heat pipes define a generally vertical plane when the manifold is installed for operation.
A pre-selected number of thermoelectric modules are arranged for thermal communication with the upper cylinder. The upper cylinder defines a surface to thermally communicate with an aligned array of thermoelectric modules presented so that their cooling faces are in thermal communication with the upper cylinder of a cooling manifold. The interior volume of the manifold will be charged with a suitable thermally conductive fluid that will circulate within the internal volume during operation of the air conditioning device. The heat pipes define a plurality of vertically arranged, elongated capillaries that allow fluid communication of the thermally conductive fluid between the upper and lower cylinders of the self contained manifold. The thermally conductive fluid contained within the manifold will tend to flow within the internal channels of the heat pipes due in part to the cooling effect upon the fluid caused by the heat transfer process affected between the cooling faces of the thermoelectric modules and the upper cylinder of the manifold. In addition, the thermally conductive fluid will tend to flow in part due to the capillary action exerted on the fluid charged within the interior volume of the manifold, and extending within the capillaries of the heat pipes. One of the advantages of the invention is that it is unnecessary to provide a circulating pump to circulate a thermally conductive fluid within the interior chamber of the heat pipes. Although there may be instances where a circulating pump may be added for that purpose, such a pump would not be necessary to circulate the thermally conductive fluid filled within the interior volume of the upper cylinder, heat pipes and lower cylinder.
During assembly, an access port (not shown) may be provided on the manifold to evacuate entrapped air from within the internal chambers of the lower cylinder, upper cylinder and capillaries within the heat pipes. In a preferred embodiment, the interior chamber of the heat pipes is drained of entrapped air so a substantial vacuum is created. Thereafter, the interior chamber of the lower cylinder, upper cylinder and capillaries of the heat pipes are filled with an effective amount of the thermally conductive fluid until a substantial portion of the interior volume of that structure is filled with a liquid phase of the thermally conductive fluid. The remaining portion of the interior volume is filled with the vapor phase of the selected thermally conductive fluid. After the manifold is charged with the appropriate fluid, the access port may be closed by applying a suitable stopper or cap.
As noted above, a thermally conductive fluid is provided within the enclosed fluid reservoir of the manifold. Heat exchange occurs through the operation of the thermoelectric modules and the repeated evaporation and condensation of the thermally conductive fluid within the fluid reservoir of the manifold.
In a preferred embodiment, the fluid within the interior volume is filled until the liquid phase occupies about 40% to 70% of that interior volume. The vapor phase will occupy between about 30% and 60% of that interior volume, in a preferred embodiment. These amounts are preferred charging ratios. However, other operatively effective amounts may be chosen to meet selected design criteria.
In a further preferred embodiment of the invention, the capillary channels in a heat pipe are generally rectangular tubes defined by the interior walls of each heat pipe. Preferably, the interior walls extend orthogonally from one face of the heat pipe to the opposing face of the heat pipe. However, the capillaries may be manufactured to have other cross-sectional configurations that are not necessarily square or rectangular in shape. The relative size of the capillaries may vary according to the design requirements and characteristics of the desired heat exchange system. In a preferred system directed to the use of water based thermally conductive fluid systems, the diameter of the capillaries will typically range below about 4 mm. In some instances, it may be desirable to provide additives or other fluids to enhance the physical properties of the fluid circulating within the capillaries. Consequently, the diameter of the capillaries may be adjusted to accommodate the particular characteristics of a specific fluid selected for use in the system.
In another preferred embodiment, the capillaries are arranged in a single layer of capillaries within the outer walls of a given heat pipe. In other instances, multiple layers of capillaries may be provided within the outer walls of each heat pipe, although in many cases, such an arrangement may not be preferred.
The heat pipes, upper cylinder, and lower cylinder are preferably made of relatively strong, resilient, and thermally conductive material and most preferably, a metal which is not susceptible to excessive corrosion. Aluminum is a particularly useful material of construction for many applications of the present invention. Of course, persons skilled in the art will understand that other materials, including other metals, alloys, or non metallic materials may be desirable for use in the particular conditions and circumstances under consideration. Similarly, other components of an air conditioner and air conditioning assembly are preferably made of compatible materials that will exhibit similar advantages and benefits.
A variety of thermally conductive fluids may be used according to the design requirements of a particular system. For example, in heating applications, many conventional fluids including water, acetone, ethanol and methanol may be desirable as relatively low-cost thermally conductive fluid choices for use within the manifold. It will be appreciated that the foregoing examples of potentially useful fluids are merely illustrative and are not intended to represent an exhaustive list of all suitable thermally conductive fluids.
In some heat exchange systems, capillaries having cross-sectional diameters of about 4 mm in diameter will be particularly efficient in heat transfer applications. In another instances, it may be desirable to use capillaries with smaller effective diameters. Capillaries that are generally rectangular when viewed in cross-section may have dimensions of 1 mmxc3x971.4 mm or lower. In other instances, the capillaries may have cross-sectional dimensions of about 0.5 mmxc3x970.6 mm. Of course, other sizes of capillaries may be selected based on various design considerations.
In other embodiments, a plurality of vertically oriented manifolds may be combined to form a heat exchange arrangement featuring a heating component and a cooling component. The heating component is featured by one or more upper heating manifolds secured on opposite sides of one or more lower cooling manifolds. The overall heat exchange arrangement, may be formed by alternating heating and cooling manifolds in alternating arrangements where the cooling manifolds are positioned between opposing pairs of heating manifolds. In this example, a plurality of thermoelectric modules are sandwiched between an upwardly disposed heating manifold and an adjacent, downwardly disposed cooling manifold. The thermoelectric modules are arranged so that all of the cooling faces of such modules are in thermal communication with the upper cylinder of the cooling manifold. All of the heating faces of the intermediately disposed thermoelectric modules are positioned to be in thermal communication with the lower cylinder of the adjacent, upwardly disposed heating manifold. A combined heating and cooling device for automotive and other applications may be provided with an air control feature to selectively direct air across the heating or cooling manifolds to condition that air prior to entry into an automobile or other structure.
In other embodiments of the invention, a fan or other blower element may be provided for directing air flow across the heat pipes of one or more manifolds provided in a heating or cooling device of the present invention.
In some embodiments of the invention, it may be desirable to incorporate a warm water supply for generating heated water (rather than warmed air) by directing a flow of water in thermal communication with the heating faces of a selected number of thermoelectric modules. The cooling faces of the modules will be aligned in a cooling array, in thermal communication with a cooling manifold in an air conditioning device.
In another preferred embodiment of the present invention, the air conditioner comprises a heat exchange manifold in which the generally planar, elongated heat pipes are arranged in a planar array along the longitudinal axes of the upper and lower cylinders. The upper and lower cylinders are positioned in parallel, with the elongated heat pipes extending between the two cylinders. The heat pipes are positioned in parallel to each other so that a gap is formed between opposing faces of the heat pipes. The gaps between the heat pipes provide channels for air flow, for thermal communication across the faces of the heat pipes during a cooling cycle. In some embodiments, the surfaces of the heat pipes may be textured or modified to increase their effective surface area for heat transfer between the transported air (or other fluid) and the heat pipes. For example, inter-connecting ribs, fins or other projections may be provided between adjacent heat pipes in order to improve the heat transfer between flowing air and the heat pipes.
Thermoelectric modules are also known in the art as Peltier devices. Earlier examples of Peltier devices are generally wafer-like structures that produce heat and cooling effects upon application of electric current. In most embodiments of the invention, DC power sources will be utilized to produce uniform heating or cooling effects upon a target body or system component.
Other embodiments, and aspects of the invention will become apparent upon a review of the details and explanations of the invention and upon a review of the attached drawings which follow within this application.